DIGITALNA ARHIVA ŠUMARSKOG LISTA
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possible number of different alleles (Mmax) and the average number of alleles per polymorphic locus (A/L). Genetic diversity was quantified using parameters of the observed level of heterozygosity (Ho) and the conditional heterozygosity (Hc; Gregorius et al. 1986), effective number of alleles per locus (ν; Gregorius 1978, 1987), hypothetical gametic multilocus diversity (νgam) and the level of genetic differentiation among individuals within a population (δT; Gregorius 1987) which, with larger samples, is the same as the share of expected heterozygosity, created by random mating or panmixia (He; Nei 1973). For each polymorphic locus, χ2 tests of deviation from the corresponding Hardy-Weinberg expected genotypic structures as well as Hardy-Weinberg heterozigosity at the level α = 0.05 were carried out to test whether the observed genotypic structure deviates from panmixia and whether there was a significant excess or deficiency of heterozygotes in a population. The degree of differentiation between populations was measured with χ2 tests of homogeneity among allele frequencies for particular gene loci at the level α = 0.05 and genetic distances (d0) proposed by Gregorius (1974). All computation was performed with GSED software (Gillet 1998) for analyzing genetic structures from electrophoresis data.
The results of genetic comparison of sampled beech populations at Vrhovo and Kozarje are shown in Tables 2 and 3 for 16 isozyme gene loci. Minor polymorphism in both populations was observed at nine loci: Aat-A, Aco-A, Mdh-A, Mdh-B, Mnr-A, Pgi-B, Skdh-A, 6-Pgdh-B, 6-Pgdh-C with the frequency of the major allele always higher than 75 %. Four loci (Aat-B, Mdh-C, Per-B, Pgm-A) showed a clear major polymorphism with the same predominant allele in both populations. A distinct transition between low and high levels of polymorphism in the test populations were found at three loci. In the Vrhovo population (from a lower altitude), minor polymorphism was expressed at loci Aco-B and Idh-A and major polymorphism at locus 6-Pgdh-A. In the Kozarje population (from a higher altitude), a clear minor polymorphism was expressed at locus 6-Pgdh-A and clear major polymorphism at loci Aco-B and Idh-A. For example: alleles Aco-B2, Idh-A2 and 6-Pgdh-A4 in the Vrhovo population reached 8 %, 12 %, 28 %, respectively, in the Kozarje population 20 %, 25 % and 11 %, respectively. A clear differentiation between the two populations was also observed at locus 6-Pgdh-B, where the population of beech from higher altitude of the Gorjanci Mountains revealed much higher frequency of the second dominant allele B1 (16 %) in comparison to the 6 % frequency at the lower altitude population.